how to make mockito test case with Constructor injection - kotlin

Question

I want to make junit test case with mockito
there are Classes.
MyProps : the properties data class #Configuration
MyService : my main logic #Service class
MyClient : webClient class #Component
how to test myService result logic with mockito?? and how to make data class(MyProps) simply???
there error is like this :
You haven't provided the instance at field declaration so I tried to construct the instance.
However the constructor or the initialization block threw an exception : Parameter specified as non-null is null:
#Configuration
#ConfigurationProperties("application.something")
class MyProps {
lateinit var broker: String
lateinit var url: String
}
#Service
class MyService(private val client: MyClient,
private val myProps: MyProps
){
fun getReulst(params: Params): Flux<MyEntity> {
// some logic, and I want check this part result
return client.get(params)
}
}
#Component
class MyClient(val myProps: MyProps) {
private val webClient: WebClient = WebClient.create()
fun get(params: Params): Flux<MyEntity> {
val params = BodyInserters.fromValue(query)
return webClient
.post()
.uri(myProps.broker)
.contentType(MediaType.APPLICATION_JSON)
.accept(MediaType.APPLICATION_JSON)
.body(params)
.retrieve()
.bodyToFlux(MyEntity::class.java)
}
}
here is test code
//----------------
#SpringBootTest(classes = [MyService::class, MyProps::class, MyClient::class])
#TestInstance(TestInstance.Lifecycle.PER_CLASS)
class MyServiceTest {
#MockBean
private lateinit var myProps: MyProps
#MockBean
private lateinit var myClient: MyClient
#InjectMocks
private lateinit var countService: MyService
#BeforeEach
fun mock() {
given(myProps.broker).willReturn("http://url.com")
given(myProps.web).willReturn("something")
given(myClient.get2(query)).willReturn(
Flux.fromIterable(listOf(
MyEntity("2020-03-22", Count(1)),
MyEntity("2020-03-23", Count(2)),
MyEntity("2020-03-24", Count(3)),
MyEntity("2020-03-25", Count(6)),
MyEntity("2020-03-26", Count(5)),
MyEntity("2020-03-27", Count(4))
))
)
MockitoAnnotations.initMocks(this)
}
#Test
fun `I want to check!! here`(){
val param = Params(1,2,3) // some params
myService.getReulst(param).subscribe() // <- here is error maybe param is null... why??
}
}

Answer 1

Since you're injecting mocks into your service you don't really need a full-blown spring boot test. This will make your tests faster.
Furthermore, since you're mocking MyClient, you're not really calling its code. Therefore whatever happens in MyClient can be ignored here. You'll cover it in its own test.
Here's how I'd write this test with JUnit 5 (you'll have to translate it to JUnit 4 if you're still on it):
#ExtendWith(MockitoExtension::class)
class MyServiceTest(
#Mock val myProps: MyProps,
#Mock val myClient: MyClient
) {
// you can use #InjectMocks if you prefer
val countService: MyService = MyService(myProps, myClient)
#BeforeEach
fun mock() {
// you only need these if they're called in MyService
`when`(myProps.broker).thenReturn("http://url.com")
`when`(myProps.web).thenReturn("something")
`when`(myClient.get(Params(1,2,3))).thenReturn(
Flux.fromIterable(listOf(
MyEntity("2020-03-22", Count(1)),
MyEntity("2020-03-23", Count(2)),
MyEntity("2020-03-24", Count(3)),
MyEntity("2020-03-25", Count(6)),
MyEntity("2020-03-26", Count(5)),
MyEntity("2020-03-27", Count(4))
))
)
}
#Test
fun `I want to check!! here`(){
val param = Params(1,2,3)
myService.getReulst(param).subscribe()
}
}